In 2014 at the Seattle Pacific University an assailant using a shot gun killed one person and injured two others. The shooter shot one person outside then entered the lobby of Otto Miller Hall on the SPU campus. He pointed the gun at students sitting at tables but was not noticed. Another student came down some stairs and he pointed the gun and fired wounding the student who was able to turn and run back up the stairs. That is when another male student ran in with his pepper spray and sprayed the shooter who he then tackled. He was able to disarm the shooter and took the gun away and placed it in another room. In the security footage you can see the shooter laying on the floor suffering from the effects of the pepper spray.
I don’t recommend running toward anyone with a gun armed only with pepper spray but if faced with that type of threat pepper spray is very effective. It will cause the attacker to become disoriented and unable to see clearly. This gives you the chance to get away or if necessary disarm the attacker. Always keep in mind disarming an attacker is very dangerous and getting away should be your priority. Using a spray that also has an ultraviolet dye will help authorities identify the suspect later.